From heart risk to muscle boost: new research unlocks the double-edged sword of red meat—here’s what you need to know to eat smart.
Red Meat Amino Acids for Beginners: A Narrative Review. Image Credit: Natalia Lisovskaya / Shutterstock
Red meat is considered to be a potential risk factor for a range of cardiometabolic diseases when overconsumed or prepared using high-temperature methods (e.g., grilling), despite being a complete source of all essential and non-essential amino acids as well as bioactive amino acid derivatives.
In a review article published in the journal Nutrients, researchers at Texas Tech University, USA, elaborately discussed the impact of red meat proteins and amino acids on human health and disease.
Background
Red and white meat are two major sources of dietary amino acids, fatty acids, and micronutrients worldwide. While white meat refers to skeletal muscles from poultry like chicken and turkey, red meat refers to skeletal muscles from mammals like beef, pork, and lamb.
Red meat is the complete source of all essential and non-essential amino acids and a major source of heme-iron required for muscle growth and cardiovascular health. Despite providing essential micronutrients, red meat has been found to be associated with a range of health conditions, including cardiovascular disease, metabolic disorders, and even colorectal cancer when consumed excessively or processed.
Existing evidence indicates that the amount of intake and the processing methods are major determinants of red meat-related diseases. Meat and meat products are processed for various purposes, including preservation, storage, flavor, or protection from pathogens. Overconsumption of red meat or regular consumption of highly processed red meat has been found to increase the risk of health adversities.
Concentrations of cholesterol, iron, saturated, and total fat measured in 100 g of meat protein, from 13 different types of meat. Meats surveyed were ground bison, beef, lamb, and turkey, flank steak, pork tenderloin, turkey leg, chicken nuggets, chicken breast, clams, shrimp, tuna, and salmon. Outliers were adjusted to fit on the graph for shrimp cholesterol (195 mg) and clam iron (26 mg). Original data from the USDA nutrient laboratory SR-21.
Composition of Red Meat
Red meat contains various fatty acids, including saturated, polyunsaturated, omega-3, and trans fatty acids. Red meat-related health adversities are primarily associated with the type and quantity of saturated fatty acids, which differ between animals depending on the kind of foods these animals are consuming. The cooking process is another vital determinant of fatty acid profiles in red meat.
Red meat is a major source of many vitamins and minerals, including vitamins B, A, and E, copper, zinc, selenium, and iron. Compared to fat-soluble vitamins, such as vitamins A and E, water-soluble vitamins, especially vitamin B12, are present at high concentrations in red meat.
The amount of vitamin B in red meat depends on its lipid content. A reduction in lipid quantity due to cooking leads to an induction in vitamin B quantity. Similarly, red meat from leaner animals contains higher amounts of vitamin B than from animals with high body fat.
Unlike vitamin content, most mineral concentrations in red meat cannot be easily modified in livestock through dietary modifications. Dietary consumption of any red meat in the same quantity is likely to provide similar amounts of most minerals, except for iron. In this context, evidence indicates that the amount of iron varies significantly between different categories of red meat.
Red meat contains all essential amino acids and 11 non-essential or semi-essential amino acids used by the human body. Depending on the animal species, 100 grams of cooked red meat contains approximately 28–36 grams of protein. Additionally, red meat provides important bioactive amino acid derivatives such as taurine, carnitine, creatine, and glutathione, which play roles in muscle function, antioxidant defense, and energy metabolism.
The sex of the source animal may also influence amino acid metabolism in humans, with emerging research suggesting sex-specific responses to dietary amino acids.
Studies assessing amino acid quantities in red meat indicate that beef and pork have up to 32% differences in essential amino acid proportions and more than 100% differences in non-essential amino acid proportions. The variation in amino acid profiles in red meat also depends on the age and sex of the source animal.
Health Implications of Red Meat Amino Acids
Red meat has been indicated as a major contributor to the increasing incidence of cardiovascular and metabolic disorders in contexts of excessive intake. Considering the health benefits of macro and micronutrients present in red meat, this review's authors emphasized the importance of considering the roles of red meat amino acid profiles in modulating human health and disease.
Cardiovascular Disease
The risk of cardiovascular disease due to red meat intake can be attributed to the metabolite trimethylamine-N-oxide (TMAO), which is produced by the gut microbiota from carnitine and choline, two nutrients abundantly present in red meat. However, fish and marine invertebrates are the most abundant dietary sources of TMAO, and the direct role of red meat in elevating TMAO-linked cardiovascular risk remains under investigation. Serum TMAO concentrations are typically altered through modification of dietary protein sources. The metabolism of red meat carnitine into TMAO could be a major finding in the characterization of dietary-related diseases.
Obesity and Type 2 Diabetes
Overconsumption of red meat or processed red meat has been found to increase the risk of obesity. On the other hand, meat-only dietary patterns have recently gained popularity as a potential weight-loss strategy. These patterns claim to reduce total body and fat mass while maintaining fat-free or lean mass.
Overconsumption of red meat has also been found to increase the risk of type 2 diabetes. However, most studies in this area have rarely considered the types of red meat and relied heavily on self-reporting without a metric for physical activity.
In cases of diabetes and obesity, satiety signaling plays a key role in overconsumption of foods. Red meat is a complete protein source, so its intake results in increased blood levels of amino acids, which subsequently increase the levels of satiety-related hormones and suppress the feeling of hunger.
Low-fat red meat has been found to increase gastric leptin (a hormone that controls hunger and satiety) secretion by elevating amino acid levels. Chronically high consumption of both red meat and processed meat leads to increases in serum leptin due to elevated fat mass in consumers. These observations indicate that red meat-related changes in leptin levels are confounded by high-fat mass in consumers.
Regarding diabetes-related complications, studies have identified connections with elevated levels of specific amino acids. While elevated serum glutamine has been identified as a contributing factor for diabetes retinopathies, supplementation with amino acid serine has been found to delay the onset of diabetic neuropathy.
These observations highlight the significance of exploring amino acid profiles in red meat to contextualize nutritional sources for maintaining health and preventing disease.
Colorectal Cancer
The carcinogenic effects of red meat are associated with heterocyclic aromatic amines and polycyclic aromatic hydrocarbons, which are produced during the cooking process, especially during high-temperature cooking with direct contact with the heat source, such as grilling or pan-frying.
Metabolic-Disorder Associated Steatotic Liver Disease (MASLD)
Red meat-induced risk of MASLD has particularly been observed in obese individuals. Dietary amino acids, especially essential amino acids, as well as heme iron, have been identified as the key contributors to de novo lipogenesis in the liver in obese mice.
A common trend in obesity-related diseases like MASLD is that obese individuals tend to overconsume red meat, highlighting a dose-dependent relationship between consumption of red meat and MASLD development.
Gut Microbiome
The review also emphasizes that red meat intake may influence gut microbiome composition, which plays a critical role in modulating health and disease. Although red meat is a high-quality protein source, its effects on gut bacteria, including those involved in TMAO production, are still under investigation. The digestibility of red meat’s amino acids may limit their direct role in supporting gut microbiota, but indirect effects on microbial metabolites may occur.
Significance
The current review covers many areas in human health and disease where red meat consumption might provide beneficial outcomes when consumed in moderation. Red meat provides the highest quantities of nutrients that can potentially improve skeletal muscle growth and subsequently improve the quality of life in older individuals. However, the paper notes that while higher protein intake may benefit those over 66, it could increase mortality risk in middle-aged populations (50–65), underscoring the importance of age-specific dietary guidance.
Branched-chain amino acids present in red meat play crucial roles in protein synthesis required for muscle repair. In addition to the vital roles red meat amino acids play in muscle growth, recovery, and maintenance, red meat fatty acids can provide energy to muscle cells through β-oxidation. Furthermore, amino acid derivatives such as creatine and carnosine support muscle energy metabolism and antioxidant defense, making red meat beneficial for athletes.
Overall, the review highlights the need for further investigations to determine how best to incorporate red meat into a healthy diet while considering preparation methods, portion sizes, and individual health contexts.